heater's fan problem

[bensep]

Hi, I own a vw sharon TDI 1999, when I switch the heater on the fan works for 10 secons and then stops, when I switch it off and on again after 5 minutes it comes on for another 10 seconds and gradually slows down and stops, it's the same when I put the aircon on, any help would be appreciated.
Thanks,
Ben:(

[Andygrove]

Hi, new to this so hope this is ok.
I have a 1996 sharan same problem as you mine turned out to be the carbon brushes on the fan motor (behind glovebox).
Andy